jquery event after html() function

Is there a way to launch an event after html() has been fired? Such as:

$.post("ajax.php", {data :data}, function(data){
   $("#countries").html(data, function(){
      alert("test");
   });
});

This is not working.

EDIT: I am asking this because I want to do few things(another call) with the information coming from the call... I wanted to simplify the example...I guess programmers always want to know why...

So here it is the example updated

 $.post("ajax.php", {data :data}, function(data){
   $("#countries").html(data, function(){
        var id = $("#countries option:selected").attr("id");
        getRegions(id);
   });
});